Final answer:
The founder effect explains the difference in allele L frequency in shrimps between the cave and the open area due to a small group of founders who may have had different allele frequencies than the original population.
Step-by-step explanation:
The difference in percentage of shrimps with allele L between those in the cave and in the open can be attributed to the founder effect. This occurs when a new population is started by a small number of individuals from a larger population. Due to the small size of this founding group, the allele frequencies might not be representative of the original population. For instance, if these founding shrimps happened to carry allele L more frequently than the average in the original population, their descendants would also display a higher frequency of this allele, leading to the observed variation between cave and open-area shrimps.
An example of the founder effect is the genetic divergences in the Afrikaner population due to a small group of Dutch settlers who carried unusual mutations, resulting in higher incidences of diseases like Huntington's disease (HD) and Fanconi anemia (FA) in their descendants compared to the general population.